Component selection advice

Start from the electrical job, then narrow by availability, package size, qualification needs, and the supply chain your team actually uses.

Resistors

• Choose technology by the role in the circuit:
  • Thick film: default for commodity pullups, dividers, biasing, LEDs, and low-cost general SMT use.
  • Thin film: use for precision gain setting, filtering, references, low noise, and tighter temperature coefficient needs.
  • Metal film: useful where stable precision, low noise, or through-hole/lead-based families are preferred.
  • Current-sense: choose for low-value shunts; check power rating, Kelvin options, TCR, and pulse rating.
  • Anti-sulfur: use for industrial, outdoor, automotive, or other sulfur/corrosion-prone environments.
  • Surge/high-voltage: use for inputs, protection, discharge paths, mains-adjacent circuits, and high divider voltages.
  • Wide-terminal/high-power: use when thermal spreading, board heat transfer, or power density matters.
  • Automotive/high-reliability: use AEC-Q200 or qualified series when the environment, customer, or lifecycle requires it.
• Keep the core generic set practical:
  • Panasonic: baseline mainstream anchor.
  • Yageo: broad commodity second source.
  • Vishay: industrial, automotive, precision, and higher-reliability coverage.
  • KOA Speer: precision, anti-sulfur, current-sense, surge, high-voltage, and wide-terminal options.
  • Stackpole: common North American thick-film and thin-film second source.
  • Bourns: current-sense, surge, sulfur-resistant, and automotive variants.
  • ROHM: compact, automotive, and higher-power mainstream coverage.
• Add specialist or volume vendors only when they solve a real sourcing or performance need:
  • Susumu: precision analog, instrumentation, and thin-film stability.
  • Samsung Electro-Mechanics: optional high-volume Asian passive supply chain coverage.

Capacitors

• Choose the dielectric before the vendor:
  • C0G/NP0: timing, filters, RF matching, precision analog, and other stability-sensitive circuits.
  • X7R: default MLCC choice for general decoupling and moderate-value capacitance over temperature.
  • X5R: compact local bypassing when the temperature range and tolerance stack are understood.
• Do not select MLCCs by nominal capacitance alone:
  • Derate voltage enough for the circuit, environment, and reliability target.
  • Check DC-bias curves; small high-value MLCCs can lose a large fraction of effective capacitance.
  • Treat package size as an electrical choice, not just a layout choice; 0402 and 0805 parts with the same nominal value may behave very differently.
• Use package size intentionally:
  • Smaller packages help dense local decoupling and low parasitics.
  • Larger packages often improve voltage headroom, DC-bias behavior, and availability.
  • Watch mechanical cracking risk on larger MLCCs, especially near board edges, connectors, or high-flex areas.
• Leave MLCCs when another capacitor type fits better:
  • Polymer: bulk output capacitance with low ESR.
  • Tantalum: compact bulk capacitance when surge and derating rules are acceptable.
  • Aluminum electrolytic: cost-effective bulk energy storage or high capacitance.
  • Film: precision, low loss, AC, pulse, snubber, or safety-related applications.

Inductors

• Separate beads from energy-storage inductors:
  • Ferrite beads: lossy EMI parts for isolating noise over a frequency range; not power inductors.
  • Power inductors: switching-converter and filter parts where saturation, ripple current, DCR, and thermals drive selection.
• Check the current ratings behind the headline number:
  • Saturation current: where inductance falls below the useful limit.
  • Temperature-rise current: where self-heating reaches the vendor's stated limit.
  • DCR: lower DCR improves efficiency but usually costs size, price, or availability.
  • Inductance tolerance and bias behavior: important for ripple, control-loop margin, and peak current.
• Account for EMI and placement:
  • Use shielded inductors near sensitive analog, RF, sensors, or high-gain circuitry.
  • Consider unshielded parts only when field coupling, emissions, and layout are benign.
  • Review audible-noise behavior when ceramic capacitors and power magnetics interact.
• Prefer vendor-qualified regulator series when available:
  • Start from regulator reference designs or design-tool recommendations.
  • Use qualified series when loop stability, thermals, emissions, or noise are tight.
  • Still verify saturation, DCR, package, temperature rise, and lifecycle availability.